Jesse Vincent uploaded the perl-5.12.0-RC3 release to the CPAN. It's important that that this release is tested to flag any potential release blockers. If none are found it'll be released as 5.12 on April 9.

Here's how you can do that:

All tests should have been successful. To install it (without touching your existing perl!) do:

Now you have an installed perl-5.12.0-RC3 in ~/perl5-rc3/installed/bin/perl. Now just configure CPAN to install modules without nagging:

And then maybe try installing your favorite CPAN modules, or bundles that suck down a lot of them (using sudo here because my ~/.cpan is owned by root):

Of course the most useful think you can do is test it on your own in-house code. All the code on the CPAN has probably been tested with 5.12 already.